The present invention relates to an inspection device for inspecting a thin plate container and a method of inspecting a thin plate container.
A thin plate container is used for storing a plurality of thin plates such as semiconductor wafers supported on stage guides at several levels. Such a thin plate container is mainly formed of a resin. In use, the thin plate container is repeatedly washed for a long period of time. Accordingly, the thin plate container tends to deform with time.
When the thin plate container deforms, the semiconductor wafers are supported on the stage guides with irregular intervals. Accordingly, when a support plate of a transport arm is inserted into the thin plate container between the semiconductor wafers for transporting the semiconductor wafer, the support plate may hit and damage one of the semiconductor wafers. In an extreme case, when the thin plate container deforms to a large extent, the semiconductor wafer may be broken.
In order to prevent the transport arm from hitting the semiconductor wafer, the thin plate container is inspected regularly with an inspection device. When a conventional inspection device inspects the thin plate container, first, a support plate of a transport arm is inserted between the semiconductor wafers supported on the stage guides at several levels in the thin plate container. Then, an operator visually adjusts and sets an initial position where the support plate is situated between the semiconductor wafers with an equal interval.
Then, the operator adjusts heights of four cassette legs disposed on a bottom surface of the thin plate container, so that it is confirmed that the support plate does not contact with the semiconductor wafers within upper and lower limits of a variance in a supporting position of the semiconductor wafers. Afterward, the operator inspects deformation of the thin plate container (refer to Patent Reference).
Patent Reference: Japanese Patent Publication No. 2004-072067
In the conventional inspection device described above, after the operator visually confirms that the support plate is situated between the semiconductor wafers with an equal interval, the operator adjusts the heights of the cassette legs to confirm that the support plate does not contact with the semiconductor wafers within the upper and lower limits of the variance in the supporting position of the semiconductor wafers, thereby inspecting the deformation of the thin plate container. Accordingly, when the support plate is situated between the semiconductor wafers with a small interval, it is difficult to visually confirm that the support plate is situated between the semiconductor wafers with an equal interval. As a result, it is difficult to accurately set the initial position and confirm that the support plate does not contact with the semiconductor wafers within the upper and lower limits of the variance.
Further, when the operator confirms the upper and lower limits of the variance, it is necessary to adjust the cassette legs, thereby taking a long time for the inspection.
In view of the problems described above, an object of the present invention is to provide an inspection device of a thin plate container and a method of inspecting the thin plate container, in which it is possible to accurately and efficiently inspect deformation of the thin plate container.
Further objects and advantages of the invention will be apparent from the following description of the invention.